Method and means for producing solidified carbon dioxide



June 6, 1933. J. c. GOOSMANN 1912,4455

METHOD AND MEANS FOR PRODUCING SOLIDIF'IED CARBON DIOXIDE Filed Aug. 11,1928 2 Sheets-Sheet l 0 k233i m 6 N MQ N 3 QM Wk S Q 6 m $3 e kb mq axmium June 6, 1933. 1,912,443

METHOD AND MEANS FOR PRODUCING SOLIDIFIED CARBON DIOXIDE J.- c. GOOSMANNFiled Aug. 11, 1928 2 Sheets-Sheet 2 avm wn toz Jus fus C.

IIFIFIIIIIIIIII A v n a W A W W? a w n 4 a 7 MM J 5 7 c0 6 /U W PatentedJune 6, 1933 UNITED STATES'PATE NT OFFICE JUSTUS C. GODS-MANN, OFCHICAGO, ILLINOIS METHOD AND MEANS FOR PRODUCIN G SOLIDIFIED CARBONDIOXIDE Application filed August 11, 1928. Serial No. 298,992.

This invention relates to a method and apparatus for producing solidcarbon dioxide commonly known as carbon dioxide snow.

One of the objects of this invention is to provide a method andapparatus for use in producing carbon, dioxide snow which is simple,economical of manufacture, installation, operation and maintenance andhighly efficient in use.

Another object of this invention is the provision of an apparatus forthe production of solid carbon dioxide in which gaseous carbon dioxideis converted to a liquid form and subjected to several stages of coolingbefore its solidification.

A still further object of this invention involves an apparatus of theabove type in which the liquid is sub-cooled in several stages bypassing it from one container to another through pressure ratio valves.

A still further object of this invention contemplates the formation ofliquid carbon dioxide from gaseous carbon dioxide in several stages ofcompression and cooling the gas between each stage of compression bysubjecting it to a counter flow of colder carbon dioxide gas returningfrom liquid coolers.

Another object of this invention contemplates in the final step offorming carbon dioxide snow by delivering the sub-cooled liquid from aliquid cooler to a snow forming machine.

Further objects of this invention will appear more fully hereinafter.

This invention consists substantially in the combination, construction,arrangement and relative location of parts as well as the procedureemployed in connection therewith, all as will be more fully set forthherein after, as shown by the accompanying drawings and finally pointedout in the appended claims.

Referring to the drawings in which the same reference numerals will beused throughout the several views to indicate the same or similar parts,

Figure 1 is a diagrammatic view illustrating the apparatus and theassociation thereof employed in accordance with this invention and bymeans of which the process thereof is utilized;

Fig. 2 is a vertical cross sectional view of a snow machine in which thecarbon dioxide snow is formed in combination with means for compressingthe snow into blocks.

a Fig. 3 is a vertical cross sectional view of 1e invention.

This invention pertains to the rational production of solidified carbondioxide, or carbon dioxide snow at low pressure and the sub-cooling ofthe liquid CO before solidification by partial evaporation in successivesteps, as well as by the employment of heat exchangers for the coolingof the liquid by the cold CO gas returning to the compres- S'IOIIapparatus from the next lower pressure liquid cooler in counter currentflow.

A short recapitulation of the properties and characteristics of carbondioxide will no doubt be of help to appreciate the particular modusvivendi employed in this method.

The origin of the CO gas does not matter. It may be produced bycombustion, from lime kilns during the calcination of lime stone, fromalcoholic fermentation, by chemical decomposition or any other sourcefrom which carbon dioxide gas may be After this gas has been purified tomake it suitable for the purpose of solidification and its application,it must be converted from the gaseous in to the liquid state in order totake up the latent heat of a liquid, which afterwards is set free in theevaporation of the greater part of the liquid. When evaporating insuitable containers, with the influx of heat from the outside preventedas much as possible, ate erature is reached which is known as the trlplepoint of carbon dioxide, at which a part of the liquid changesrapidly-from the liquid into the solid state.

At this point, or slightly below it, the liquid may be changed into asolid, resembling opaque ice, when the receptacle in which thisconversion takes place is maintained at a pressure slightly lower thanthat of the triple point. But when it is desired to propressure ratiovalve employed in the obtained. 4

ducetmore or less loose CO crystals, resembling snow, the liquid issprayed into a receptacle of larger volume at a further reduction inpressure, until the container is filled with the same, from which it maybe removed and compressed into a hard mass of convenientsize and weightfor use as a commercial refrigerant, or for any other purpose for whichit may be fit and useful.

It is well known that carbon dioxide gas liquefies readily by the jointapplication of pressure and the cooling action of water.

The pressure is needed to raise the temperature of the gas considerablyabove that of water of ordinary temperature. At the same time it reducesthe gaseous volume to that of a liquid. The temperature of the liquiddepends upon the initial temperature of the cooling water as well asupon the efficiency of the condensing or liquefying apparatus.

The average summer temperature of the available water in the UnitedStates is below 75 F. which will liquefy CO gas and change it into aliquid of about 85.

However, there are many localities in the United States and elsewherewhere the temperature of the water in summer registers over 85 F. Inthis case the temperature of the CO leaving the condenser will be 90 andover. At this temperature carbon dioxide cannot be liquefied, in factthe possibility of liquefying it stops at 88 which is known as itscritical temperature, hence it leaves the condenser in the form of acompressed and cooled gas, a point which will become of interest later.

In order to appreciate the losses by evaporation which occur when carbondioxide is taken at condensing temperature and converted into ice orsnow at the triple point, it must be borne in mind that the temperatureof the medium has to be reduced from that of condensation orliquefaction to the triple point or the temperature of solidification;the former may ordinarily be taken at plus 85, while the latter is atminus F. The corresponding pressures in practice will then be over 1100pound gauge, for condensation and 60 pound gauge for solidification.Hence, it is necessary to reduce the pressure approximately 1040 poundsbefore solidification can possibly take place.

' Simultaneously with the reduction in pressure the temperature of themedium is reduced in a strict and definitely defined relation.

For example when the pressure is decreased from 1100 pounds and 85 tothat of the atmosphere its temperature will be lowered to minus 110 F.which is 40 lower than the temperature at the triple point orsolidification. This peculiar behavior of carbon dioxide in which itdiffers from other gases explains the fact that it cannot be dischargedinto a receptacle in the form of a liquid at atmospheric pressure,because it promptly solidifies when the pressure is reduced beyond 60pound gauge.

But liquid CO can be discharged into a receptacle in which the pressureis maintained constant at a higher pressure than 60 pounds and thetemperature which corresponds with it.

Likewise, it is of no consequence whet-her the CO is obtained from thecondenser at a temperature below or above the critical i. e. 88, so longas the confining pressure corresponds with it.

It has already been pointed out that a reduction in pressure isinevitably accompanied by a definite and corresponding reduction in thetemperature of the CO This temperature reduction does not necessarilycome from the outside by cooling through a metallic wall, it occurspromptly through its own release or rather by a partial evaporation of adefinite percentage of the total weight of the liquid. For instance, ifcompressed and cooled CO of 90 'which is above the critical temperature,and a pressure of 1230 pounds is reduced and released into anotherreceptacle in which a pressure of 350 pounds is maintained, it willimmediately liquet'y and drop to a temperature of 10, and if no coolingfrom the outside occurs, it will sacrifice slightly more than 46% of itsWeight to attain this reduced temperature.

The CO gas which has thus been generated or released from the remaining54% of the liquid is still at a pressure of 350 pounds and if returnedat this pressure to the corresponding stage of a three stage compressor,a considerable economy will be effected in recompressing andreliquefying it.

On the other hand and assuming that the compressed and cooled CO2 leftthe condenser at 90 and was then sub-cooled to 80 in a second condenseror cooler, it will lose less than 40% of its weight in its owntemperature adjustment to +10 thus showing that a second condenser orliquid sub-cooler is of economical importance in this process.

However, it is necessary to still further reduce the temperature of theliquid CO before the temperature of solidification is even approached.In order to accomplish this further reduction in pressure andtemperature a second liquid cooler may be employed in which the pressuremay be re duced to approximately to 100 pound gauge, corresponding witha temperature range of approximately between minus 64 and minus 46 F.which requires a final reduction of only a few atmospheres to reach theregion of solidification, which can easily be accomplished in a specialsolidifying apparatus. This pressure and temperature reduction againcalls for a further loss of approximately 23% out of the previouslyobtained balance varying between 60 and 54%, depending upon the startingtemperature of the CO Hence, the original quantity of the liquid has nowbeen reduced to between 31 and 37% of the original liquid quantity. I

To further enhance the economy of the method a heat exchanger may beemployed between the second and third stages of compression, utilizingthe low temperature of the released vapor at approximately minus 100 toprecool the gas leaving the second intercooler and before it enters thethird and final compression stage.

The final temperature reduction below the temperature of solidificationtakes place in a special apparatus in which the CO snow is produced,collected and weighed.

Because of the fact that the losses in liquid weight are great due tothe radical drop in the liquid temperature from condensation tosolidification the interlocation of means for the economical improvementof the method are of greatest importance of which mixing chambers,inter-coolers and heat exchangers form a prominent part.

Moreover, the return of the spent vapor into the correspondingcompression stage of the compression machinery is the means for aconsiderable economy in the required power for recompression andliquefaction since the work of compression from 100 to 350 pounds is notgreater than an equivalent ratio of compression from 350 to 1225 pounds.

Considering that solidification and snow formation takes place at apressure slightly less than 60 pounds and a temperatu e lower than minusit will be found that 10% of the remaining CO2 evaporates at this stage,leaving a balance of the original weight of 37.5 to 42%. This balancehas now been solidified at a pressure of nearly 60 pounds, whichmust beremoved to allow the snow to be handled and compressed at the pressureof the atmosphere.

However, the specific heat of the solidified CO is lower than that oftheliquid. This heat has been stated more recently by physicists to be0.284 hence the loss due to sublimation at a temperature andpressuredrop to atmospheric, that is minus 108 entails a further loss of 10%, sothat when the solidified CO finally reaches the atmos-' phere itrepresents in weight not much over 33% of the original, illustrating thefact that of 3 pounds of liquid CO only about 1. pound has been/ changedinto a solid of snow. It also follows that practically 2 pounds out of3, or 66% must be recompressed, liquefied and solidified.

Moreover, the tot-a1 power to effect this change in the process atpresent employed is roughly 150 h. p. per 1000 pounds per hour ofsolidified CO which can be reduced to below 100 h. p. in the'arrangementcontemplated, efl'ecting an operating economy in power alone ofapproximately 33% and over.

Attention may also be directed at this point to the fact that the weightof liquid CO at constant volume increases materially at the lowering ofits temperature. For illustration; liquid carbon dioxide of 86 has aweight per cubic foot of slightly.

more than 37 pounds. At "5 this weight. 'has increased to nearly 63pounds. It inform of apparatus employing the principles of thisinvention.

A pipe 1 leads from any suitable source of carbon dioxide gas to acylinder or chamber 2 which is called a mixing cylinder. A pipe 3extends from the mixing cylinder to the first stage, compressor having acylinder -1 and piston 5. This compressor is a well known type and hastwo opposed valves as has been indicated diagrammatically so that uponthe suction stroke of the piston (downward in the figure) the gas isdrawn into the cylinder through the left hand valve while the right handvalve is seated. On the compression stroke of the piston (upwardly inthe figure) the left hand valve is seated and the l'lghtJlElIld valveopens when the gas within th cylinder reaches predetermined pressure forwhich the valve is set to operate. A pipe 6 extends from the right handvalve chamber to the pipe coil 7 called the intermediate cooler; Thepipe coil 7 is intended to be cooled by running water and may be anysuitable and well known water cooler in which the gas will flow throughthe cooling coil and the water surrounding it. The other end of thecooling coil 7 is connected to another mixing cylinder 9 by means of thepipe 8. A pipe 10 connects the cylinder 9 with the cylinder 11 of thesecond stage compressor in which piston 12 operates. This compressor isthe same as the previous one with the exception that the right handvalve is set to operate at a higher pressure. A pipe 13 extends fromvalve chamber to a second pipe coil 14 also termed an intermediatecooler.

As before the pipe coil 14 is Water cooled.

The other end of the pipe coil 14 is connected by means of pipe 15 toanother pipe coil 16 within a casing 37. The coil 16 and casing 37 havebeen termed a heat exchanger. The other end of the pipe coil 16 isconnected to another mixing cylinder 17 which is in turn connectedthrough a pipe 18 to the third stage compressor having the cylinder 19and piston 20. This compressor is similar to the others with theexception that the right hand delivery valve is set at a still higherpressure than either of the other two. The right hand delivery valvechamber is connected through pipe 21 to another pipe coil 22 which istermed a condenser. The coils of this pipe are cooled by water. Theother end of the pipe coil 22 is connected to a closed cylinder orchamber 23 termed a liquid receiver. A pipe 24 connects the cylinder 23with a pressure ratio valve 25 which in turn is connected by pipe 26 toanother cylinder 27 termed the first liquid cooler. Cylinder 27 isconnected by pipes 28 and 30 through a second pressure ratio valve 29 toanother cylinder 31-termed the second liquid cooler. The cylinder 31 isconnected through pipe 32, pressure ratio valve and pipe 34 to the snowmachine 35 which will be described in more detail later. The snowmachine 35 is connected by means of pipe 36 to the casing 37 of the heatexchanger. Another pipe 38 extends from casing 37 to mixing chamber 2. Apipe 39 connects cylinder 31 with mixing cylinder 9 and a pipe 40connects cylinder 27 with mixing cylinder 17. This completes the generalassemblage of apparatus.

The snow machine will now be described in detail. The device comprises aclosed cylinder 41 within which is supported a conical chamber 42 openat both ends. The cylinder or casing 41 and conical member 42 are unitedat the bottom to form a tight joint. Projecting through the top ofcylinder 41 and a short distance into the conical chamber or member 42,are two pipes formed with nozzles 43 as indicated diagrammatically.These pipes are connected to pipe 34,

Fig. 1. The pipe 36 leading into chamber 41 is the same pipe 36 ofFig. 1. Chamber 41 is attached to a casing 44 provided with a slopingside 45. As shown the conical member 42 connects chamber 44 through anopening which is closed by a door or gate 46. The gate 46 is mounted onthe pivoted lever 47 which is counterbalanced by the weight 48. As thesnow forms on the inside of conical member 42 and rests on the gate 46it tends to open the gate against the action of weight 48. This weightmay be adjusted on arm 47 so as to permit gate 46 to open when anypredetermined weight of snow has collected thereon. By reason of theexpanding shape of member 42 the snow easily falls into chamber 44 whenthe gate opens. In

view of the fact that the snow as it falls from gate 46 will tend topile up at the side of chamber 44, the left hand wall thereof isinclined as indicated at 45. Attached to the chamber 44 at the bottom isa cylinder or casing 50 which is open at the top to coincide with theopen end of chamber 44. The chamber 50 is of any suitable shapedepending upon the shape of the finished block desired. A plunger 51 ofthe same shape as chamber 50 is adapted to slide therein towards theright under the influence of piston 53 in cylinder 52. The right handend of chamber 50 is open and arranged to be closed by means of agate 50operated by the piston rod 55, piston 57 and cylinder 56.

The pressure ratio valve will now be described.

The valve is shown comprising a member 60 provided with a longitudinalpassage 61 opemng into an annular chamber surrounding the valve member62. This valve member as shown comprises two cylindrical parts ofdifferent diameters, the upper part being of the smaller diameter andextending through a hole of larger diameter formed in the member 60.This hole is however of smaller diameter than the diameter of the largerportion of valve member 62 so that it is closed by the larger portionseating at the edge thereof. This hole when open connects the annularchamber with another chamber 63, which, in turn, is in communicationwith passage 64. Secured to the top and bottom of the member 60 are theplates 65 which are recessed to house the disks 66 and'68. The disks 66and 68 are enclosed within their recesses by means of flexiblediaphragms 67 and 69 respectively. Pins 70 extend through holes in theplate 65 and contact at one end with the disk 66 and at the other withthe plate 71. A similar plate 72 lies below plate 65 and has a centralprojection 73 extending through an opening in plate 65 so as to contactwith disk 68. The plates 71 and 72 are rigidly secured together inspaced relation at the corners by means of rods 74. A rod plates 65 and71. The rod 75 is provided with threads at the upper end on which a handwheel 77 is rotatably supported. A sprin 76 lying between the hand wheeland the plate 71 encircles the rod 75.

The valve disclosed in Fig. 3 and described above does not by itselfform the subject matter of this invention since it is a well known formof valve of this general type. Other valves which produce this resultmay equally be used, as for instance, one well known pressure ratiovalve which employs but a single diaphragm in its structure. Any valveor float by means of which in use the pressure in cylinder 31 cannotfall below a predetermined value is suitable. The idea is to provide avalve or means which will prevent a depletion of the liquid in cylinder31 and an abnormal reduction in pressure therein. Q

The operation of the apparatus in accordance with the principles of thisinvention will now be described.

Carbon dioxide gas from any suitable source is supplied at 4 or 5 poundsgauge pressure andat a temperature of 80 F. through pipe 1 to mixingcylinder 2. In this cylinder the gas at 80 F. is mixed with gas at minus50 F. flowing through pipe 38 from the heat exchanger casing 37 As aresult the warm gas being supplied from the source is cooled. .The gasmixture is then drawn through pipe 3 on the suction stroke of piston 5into cylinder 4. The delivery valve of the compressor which is the righthand valve is set to permit the escape of the gas from cylinder 4 whenit has reached the pressure in the first inter-cooler of approximately150 pounds gauge. Thus, on the compression stroke of piston 5, the gasis delivered to pipe 6 at 150 pounds pressure and at a temperature ofabout 80 F. The gas flows through coil 7 and is cooled so as to bedelivered to mixing chamber 9 at about F. Here the gas mingles with gassupplied from cylinder 31 through pipe 21% a temperature of minusapproximately The cool gas mixture flows from cylinder 9 through pipe 10to cylinder 11 of the compressor on the suction stroke of piston 12. Theright hand delivery valve of this'compressor delivers gas from thecompressor at approxlmately 400 to 450 pounds gauge, therefore on thecompression stroke of piston 12, the gas is delivered through pipe 13 tothe coil 14 at the above-pressure. The gas flows through coil 14 and iscooled somewhat and then flows through pipe 15 to coil 16 of the heatexchanger'from which it flows to cylinder 17 at a temperature near thefreezlng point of water and mingles in the cylinder with the gasdelivered from cylinder 27 through pipe 40 which is at approximately 20"F. The gas mixture is then delivered from cylinder 17 through pipe 18 tocylinder 19 of the third stage compressor on the suction stroke ofpiston 20. The right hand delivery valve of this com pressor deliversthe gas therefrom at a pressure of 1000 pounds gauge. On the compressionstroke of piston 20 the gas is delivered through pipe 21 at a pressureof 1000 pounds at a temperature of F. to the coil 22 of the condenser.The gas and liquid delivered from the condenser then flows through theliquid receiver 23. The liquid is. then permitted to flow from cylinder23 through the valve 25 into the first liquid cooler. The valve 25 isthe valve disclosed in Fig. 3 and is a pressure ratio operated rapidlyexpandin valve by means of which the pressure, which the liquid is underin cylinder 23 is reduced from 1000 pounds gauge in passing through thevalve 25 to approximately 400 pounds gauge when it reaches cylinder 27As a result of this pressure reduction 8. portion of the liquid isformed into a gas and the remaining liquid is cooled to about 20 F. ithaving been 80 F. when in cylinder 23. The gas thus collected incylinder 27 is fed back as explained before through pipe 40 to mixingcylinder 17.

The liquid is then passed from the pres sure of 400 poundsgauge ofcylinder 27 through a second pressure ratio valve 29 to cylinder 31where it reaches a pressure of 100 to 150 pounds gauge and a temperatureof approximately minus 35 F. As-a result of this second reduction inpressure the remaining liquid is further cooled and more gas is formedwhich is delivered through pipe 39 at minus 35 F. to mixing cylinder 9.

It may be pointed out here that valve 33 is'a pressure control valve forcontrolling the flow of liquid to the snow machine 35. When the liquidis delivered in cylinder 31 at a pressure of 150 pounds gauge at atemperature of minus 35 F. to the snow machine, it undergoes aconsiderable reduction in pressure since it is discharged through thenozzle 43 into the chamber of the snow machine which is at approximatelyatmospheric pressure. In the formation of snow from liquid, 9.correspondin amount of gas is ormed which flows out o pipe 36 at atemperature of minus 160 F. to the heat exchanger casing 37. This gas issomewhat warmed as it flows over the coils 18 andfthus reaches the temerature of about minus 50 F. which is t e gas delivered to mixingcylinder 2.

This represents the general cycle of operations and it is pointed outthat the temperatures and pressures given are for the purpose ofillustration only since it is apparent that other temperatures andpressures will produce useful results. The pressure ratio valve besidesforming the function of permitting the reduction in pressure alsooperates'under a condition of balanced pressures. Thus the liquid isdelivered to the valve through-passage 61 and operates on flexiblediaphragm 69 and the larger end of valve 62 causing the valve to open.'

The liquid then flows into chamber 63,

and passage 64 and operates upon diaphragm 67.. Likewise spring 76through pins 70 and projection 73 exert a pressure on the diaphragmsthrough the agency of disks 66 and 68. As a result should the pressuredrop unduly in chamber 63, the valve member 62 will be closed throughthe agency of spring 76 so that the pressure of the liquid in cylinder31 never falls below a predetermined value. The area of diaphragm 69exposed to the liquid pressure is less than the area of diaphragm 67exosed to liquid pressure. The area proportion of these diaphragms isthe same as the proportion between the pressure of liquid supplied topassage 61 and the pressure of liquid delivered to passage 64. Thetension on spring 76 is adjusted so that under normal operatingconditions, valve member 62 is depressed so that the liquid may flowfrom passage 61 to passage 64. If the liquid pressure ip either passagevaries beyond the predetermined amount, depending upon the tension onspring 76 the spring acts to close the valve. It may be pointed out herethat the plates 71 and 72 firmly united by rods 74 form a rigid cagewhich moves as a unit under the action of spring 76.

The transformation of the liquid into snow is dependentupon the pressureand the corresponding temperature. Each of these of course is dependentupon the other. The temperature of crystallization is slightly belowminus 70 F. and the pressure of crystallization is less than poundsgauge pressure.

In systems heretofore employed the liquid CO has been supplied to thesnow machine from the liquid receiver of the condenser at thetemperature which it has attained in the condenser which is usuallyabout plus 85 F. Thus, in order to convert that liquid or any part of itinto snow it is necessary to reduce the temperature below minus 70. Thismeans that only a small part of the liquid is actually converted intosnow because it is impossible to reduce in the snow machine thetemperature of all the liquid to the degree necessary to effectcrystallization.

The method of my invention greatly enhances the efliciency of systems ofthis nature by greatly increasing the amount of snow obtained from agiven amount of liquid. For example, in the old systems where thetemperature of the liquid in the liquid receiver was approximately (plus85 F. approximately 30% of the li ui is crystallized, that is threepounds of 0 will give one pound of snow on the first expansion. Inaccordance with m invention by the employment of liquid coolers, atleast twothirds of the liquid becomes crystallized that is, out of everythree pounds of liquid CO delivered to the snow machine, two pounds ofsnow are obtained. This advantageous result is obtained for thefollowing reasons: \Vith the liquid going from the receiver of thecondenser at about 80 F. to the last liquid cooler where the pressurecorresponds to about 150 pounds gauge, and the temperature minus 35 F.to the snow machine, the amount of temperature drop necessary to securecrystallization is much smaller. Therefore, in order to bring the liquidto the crystallization temperature, it is only necessary to reduce thesame approximately 35 in my system as compared with 155 in the system ofthe prior art.

It has already been pointed out that the most important advantageprovided in my method will be found 1n its greatly increased economies,particularly with reference to the saving of power.

Thus it will be seen that I have provided an exceedingly simple andhighly efficient method of eflecting maximum crystallization of liquidcarbon dioxide in a snow machine at controlling pressures andtemperatures in the manner disclosed and that I do this in such a way asto eliminate waste and maintain the efficiency of the system, utilizingall beneficial advantages obtained in the prior treatment of gas orliquid in the system.

I am, of course, aware that many changes in the details of constructionand relative arrangement of parts, steps and arrangement of steps andtemperature and pressure conditions will occur to those skilled in thisart and I do not therefore desire to be strictly limited to thedisclosure as given for purposes of illustration but rather to theprinciples and scope of this invention as it is defined in the appendedclaims.

\Vhat I desire to secure by United States Letters Patent is:

1. The method of producing carbon dioxide snow which comprises supplyingliquid carbon dioxide under pressure to a-receptacle, maintaining thepressure of the liquid at a value where the corresponding temperature isat or near the order of 35 above the temperature of crystallization andfinally discharging the liquid from said receptacle to a snow machinewhere it is solidified.

2. Apparatus of the class described, the combination with means forcompressing carbon dioxide gas and liquefying it, a container forstoring the liquid under a pressure of a value sufiicient to retain thetemperature of the liquid at about 35 above the temperature ofcrystallization, means for returning any gas that collects in saidcointainer to said com ressing and liquefying means and means ordischarging the liquid from said container to a snow machine.

3. In an apparatus of the type described, the combination of a pluralityof compressors, connections between each of said compressors, includingcooling coils and mixing cylinders, a plurality of liquid coolers and acondenser connected in series to the last compressor, connections fromsaid liquid coolers to said mixing 0 linders and means connected tothelast cy inder in said series for changing the liquid into snow.

4:. In an apparatus of the type described, the combination comprising aplurality of coolers of said series to said mixing cylinders and aconnection for said means forming the liquid into snow to the mixingcylinder connected to the inlet of the first compressor.

5. In an apparatus of the type described,

the combination comprisinga plurality of compressors each having aninlet and outlet, connections between said compressors including coolingcoils and mixing cylinders, a mixing cylinder connected to the inlet ofthe first compressor, a plurality of liquid coolers and a condenserconnected in series and to the outlet of the last of said compressors,means connected to .the last of said liquid coolers for forming theliquid into snow, connections from the last'two liq uid coolers of saidseries to said mixing cylinders, a heat exchanger in series with thecooling coil and the mixing cylinder connected to the inlet of the lastcompressor, said heat exchanger comprising a coil and easing, saidcasing being connected in series with the connection from the means forforming liquid into snow and the mixing cylinder connected to the inletof the first compressor.

6. In an apparatus of the. type described, the combination comprising aplurality of compressors arranged to successively increase the pressureof the gas passing therethrough, means in the connections between eachcompressor for cooling the gas after each compression, a plurality ofreceivers and a condenser connected in series to the last compressor,means in the connection between said receivers for reducing the pressureof the liquid as it passes from one receiver to the next and meansconnected to the last receiver of the series for changing the liquidinto snow form.

7. In a device for changing liquid carbon dioxide to snow, thecombination comprising a casing, an open ended conical member supportedwithin said casing united with said casing at its lower edge, a chamberattached to the lower edge of the casing, said conical member openinginto said chamber, means for closing said opening and means united withsaid chamber for compressing the snow into blocks.

8. In a device for changing liquid'carbon dioxide to snow, thecombination comprising a casing, an open ended conical member supportedwithin said casing united with said casing at its lower edge, a chamberattached to the lower edge of the casing, said conical member openinginto said chamber, means for closing said opening, said means forclosing said opening being adapted to release the snow within theconical member when a predetermined quantity has been formed.

9. In a device for changing liquid carbon dioxide to snow, thecombination comprising a casing, an open ended conical member supportedwithin said casing united with said casing at its lower edge, a chamberattached to the lower edge of the casing, said conical member openinginto said chamber, means for closing said opening, said means forclosing said opening being adapted to release the snow within theconical member when a predetermined quantity has been formed, and meansfor compressing the snow into blocks, comprising a piston operatedplunger and a casing opening into said chamber.

10. In an apparatus for changing liquid carbon dioxide into snow, thecombination comprising a casing, anopen ended conical member supportedin said casing and forming a tight jointwith the bottom thereof, meansprojecting into said casing and conical member for spraying the carbondioxide liquid, a chamber attached to the lower end of said casing towhich said conical member opens, a weight controlled gate for closingfining theliquid in a cylinder, delivering the liquid to other cylindersand simultaneously reducing its pressure before it enters each cylinder,supplying the gas formed at each reduction in pressure of the liquid tothe compressed gas after each compression to cool it and forming theliquid from the last cylinder into snow.

12. The method of producing carbon dioxide snow which comprisessubjecting carbon dioxide gas to suflicient pressure in successivestages of compression to liquefy it,

cooling the gas after each compression, con-- fining the liquid in acylinder delivering the liquid to other cylinders and simulta neouslyreducing its pressure before it enters each cylinder, supplying the gasformed at each reduction in pressure of the liquid to the compressed gasafter each compression to cool it and mixing the, gas formed 'the liquidtoother cylinders and simultaneously reducing its pressure before it enters each cylinder, supplying the gas formed at each reduction inpressure of the liquid to the compressed gas after each compression tocool it, utilizing the gas formed during the rming operation to cool thegas before the t compression operation .and then mixing t gas with freshgas to cool it before tion. I, 14. A method of/ producing carbon dioxidesnow comprisi g forming carbon di oxide gas into liqui form in severalsuccessive stages of co, pression, gradually reducing the temperatureand pressure of the liquid in several successive stages, utilizing thegas formed in each successive stage of pressure reduction of the liquidin cooling fresh gas at each stage of compression, converting the liquidafter its last reduction in temperature and pressure into snow andutilizing the gas formed during the snow forming operation for coolingthe fresh gas before its first stage of compression.

15. In the method of producing carbon the \rst compression operadioxidesnow which comprises subjecting carbon dioxide gas to sufiicientpressure to liquefy it, cooling the liquid after compression, confiningthe cooled liquid in a substantial body under pressure, delivering theliquid to a condition of lower pressure permitting partial evaporationthereof and forming some gas, -mixing the gas thus formed with fresh gasto cool it and then compressing it.

16. In the method of producing solidified carbon dioxide which comprisescompressing the gas in several stages, cooling the compressed gas aftereach compression, cooling the gas after final compression to liquefy it,further cooling the liquid while confined in a substantial body bypartial evaporation thereof and employing the gas produced duringpartial evaporation for cooling the fresh gas before its compression.

17. In the method of producing a liquefied gas for later solidificationcomprising compressing the gas in several stages of compression andpre-cooling the gas between each stage of compression by admixture witha colder gas.

18. In an apparatus of the type described the combination comprising aplurality of compressors, connections between each of said compressorsincluding cooling coils and mixing cylinders, a condenser connected inseries with the last compressor, liquid coolers connected in series withsaid condenser, means connected to the last cooler for solidifying theliquid, and connections from said coolers for delivering the gas formedtherein to said mixing cylinders.

19. In the method of producing solidified carbon dioxide the steps ofcompressing carbon dioxide in a plurality of stages to graduallyincrease its pressure, liquefying the compressed gas by cooling, coolingthe liquid in several stages by effecting changes in pressure andproducing gas at pressures of the order of the pressure at thecompression stages and mixing the gas formed with new gas at the variousstages of corresponding pressures before compression to cool the new gasand prepare the mixture for compress1on.

20. The method of transforming carbon dioxide from the gaseous to thesolid phase, comprising increasing the pressure of the gas in severalstages of compression, cooling the compressed gas after each compressionand mixing it with a cooler gas, the pressure and temperature conditionsat the end of the last compression operation effecting liquefaction ofthe gas, gradually reducing the pressure and temperature of the liquidthus formed in several successive stages, and finally reducing thepressure and temperature of the liquid below its critical values toeffect solidification thereof.

21. In an apparatus of the class described, the combination comprising aplurality of compressors, connections between each compressor, a coolingcoil and mixing cylinder in the connections between the first and secondcompressor and the second and third compressor, means connected to thethird compressor for causing the compressed gas to liquefy, a series oftanks connected to said means having connections therebetween includingpressure reducing valves, a connection between one of said tanks and oneof 7 said mixing cylinders, a connection between another of said tanksand the other of said mixing cylinders, and means connected to the lasttank for receiving and solidifying the liquid.

22. In an apparatus of the type described,

ing the depletion of liquid from the last of said receivers.

23. The method of making carbon dioxide ice which consists incompressing carbon dioxide by a series of compressors havingintercoolers between them, condensing the compressed fluid after passingthrough the last compressor, expanding a portion of the fluid to coolthe remainder, delivering the cooled fluid to a snow machine, andutilizing the expanded fluid to cool the gas passing to iomia1 of thecompressors, substantially as set ort 24. The method of making carbondioxide ice which consists in compressing carbon dioxide by a series ofcompressors having intercoolers between them, condensing the compressedfluid after passing through the last compressor, expanding a portion ofthe fluid to cool the remainder, delivering the cooled fluid to a snowmachine, and conducting the expanded fluid back and mixing it with thegas entering some of the compressors to pre-cool this gas, substantiallyas set forth. I

25. In a snow making system a series of compressors having cooling unitsbetween them, a condenser, a plurality of liquid cool ers, means forexpanding a portion of the compressed fluid to cool the remainder of thefluid in the first of said coolers, and means for expanding a portion ofthe fluid from said first cooler into a second cooler to cool theremaining fluid in said second cooler, and means for conducting the coldfluid from said second'cooler to a snow machine,

substantially as set forth.

26. In a snow making system a series of compressors having cooling unitsbetween them, a condenser, a plurality of liquid coolers, means forexpanding a portion of the compressed fluid to cool the remainder of thefluid in the first of said coolers, means for expanding a portion of thefluid from said first cooler into a second cooler to cool the remainingfluid in said second cooler, means for conducting the cold fluid fromsaid second cooler to a snow machine, and means for conducting coldexhaust" gas from the snow machine to the intake of one of thecompressor units, substantially as set forth;.

27. In an apparatus of the type described, the combination comprising asource of liquid carbon dioxide, means connected thereto for cooling theliquid by partial evaporation, means for forming the liquid into snowconnected to said cooling means, and means for compressing the gasdelivered from said cooling means and snow forming means to a'predetermined pressure.

'28. Apparatus for preparing carbon dioxlde gas for conversion intosnow, comprising means for liquefying the gas, a container for storingthe liquid, a pipe connection between said means and said container,

JUSTUS C. GOOSMANN.

